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I recently bought an esata external enclosure to use with my western digital elements external backup hard drive. I would prefer usb 3.0 since my case-motherboard has it but this one was on sale. Even though usb 3.0's top speeds are much faster than esata, real world speeds when using hard drives are about the same. In fact, esata might even be slightly faster for hard drives.

Many computers don't have esata ports and macs can't use usb 3.0 in case anyone was wondering. Also, the USB 3.0 port is new but a usb 3.0 device will still work in a 2.0 port and vice versa, just at the 2.0 speeds. I did notice some weird things, for example, when my 2.0 flash drive was plugged into the 3.0 port, it wasn't showing up under a windows virtual machine. I think there are still some minor compatibility bugs to work out as the usb 3.0 comes from an additional chip on the mobo.

My mobo has an esata port so I can hot swap it. Also, I was pleasantly surprised that they put a good hard drive in the WD enclosure. I estimate transfer speeds jumped to around 80-90 mb/second. 2:
The video shows disassembly of the WD elements hard drive case and my new enclosure.http://www.youtube.com/watch?v=2gjnBxywuWc

I must have been napping and missed those two coming on the market... (I still have one dedicated system running Windoze XP that has been sitting around waiting for me to hook it up... Perhaps I should sleep a bit less...)